Its so easy in SciFi to throw your plot to the window and start writing really cool chapters which don't really make sense. This kind of reckless writing will lead to a story that is too fast paced and difficult to understand and will eventually put off any reader.

I've mentioned before about logic and explanation in SciFi books, and how planning is vital. Don't just start imagining these random plot twists which sound cool in your head, because I can assure you that you will get bored of this new story line in a few chapters.

I've made this mistake so many times when writing SciFi which meant my books were random, sounded unthought out and to be honest they all suck. Stick with your plan, and if you want to make changes plan it all out. Don't just jump right in there and switch everything up.